JPS60101727A - Production of magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent wear resistance, running durability, etc. by coating a crystalline high polymer soln. on a base plate having good surface smoothness and drying the coating to form an undercoating layer having wrinkle-like projections of a specific value or below in surface roughness then forming a thin ferromagnetic film. CONSTITUTION:A crystalline high polymer soln., for example, a dichloroacetic acid soln. of satd. polyester such as polyethylene terephthalate, a phenolic soln. of nylon 6 is coated on the surface of a film having good surface smoothness such as a polyester film or metallic sheet or the like, for example, a film having <=0.01 Ra value specified in JIS B-0601 and is dried to form an undercoating layer which has about 0.1-5mu thickness, has uniform surface roughness of 0.03- 0.5mu max. height and is formed with fine wrinkle-like projections. A thin ferromagnetic layer is formed on the undercoating layer by electroplating, vaccum deposition, etc. and using a metal such as Co, Ni, Fe, and the alloy thereof, by which the recording medium having an excellent magnetic characteristic, running durability, etc. and extremely less drop-out is obtd.

Description

【発明の詳細な説明】 産業上の利用分野 本発明は、ビデオテープレコーダに用いる高密度記録ｐ
ｆ生に適した磁気記録媒体の製造方法に関する。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a high-density recording medium for use in video tape recorders.
The present invention relates to a method of manufacturing a magnetic recording medium suitable for f-rays.

従来例の溝成とその問題点 電気メッキ、無電解メッキ、真空蒸着、ス・（ツタリン
グ、イオンブレーティング等の方法で強磁性薄膜をフィ
ルム、シート等の支持体上に形成させて得られる磁気テ
ープは、従来の塗布型テープに比べて磁性層の厚みを約
１桁小さくすることが可能で高密度記録に適したもので
ある。これらの支持体としては、通常、二軸延伸された
ポリエステルフィルムが使用されるが、その中には表面
の滑り住改善のために、５ｉｎ２．　ＴｉＯ２，Ａ７１
２０５等の無機微粒子が混入されており、その一部分が
支持体表面に突出している。磁性層形成面においては、
この突起が磁気特性に悪い影響を与える。Conventional groove formation and its problemsMagnetism obtained by forming a ferromagnetic thin film on a support such as a film or sheet by methods such as electroplating, electroless plating, vacuum deposition, stumbling, and ion blating. These tapes are suitable for high-density recording because the thickness of the magnetic layer can be reduced by about an order of magnitude compared to conventional coated tapes.The support for these tapes is usually biaxially oriented polyester. A film is used, including a 5in2.
Inorganic fine particles such as No. 205 are mixed in, and a portion thereof protrudes from the surface of the support. In terms of magnetic layer formation,
These protrusions have a negative effect on magnetic properties.

強磁性薄膜型磁気記録媒体においては、強磁性薄膜の厚
さが通常０．１〜０．５μｍ程度と小さく支持体表面の
形状がほとんどそのまま磁気記録媒体の表面形状となる
ため、支持体上に粗大突起が存在するとそれがドロップ
アウトの原因となる。In ferromagnetic thin film magnetic recording media, the thickness of the ferromagnetic thin film is usually about 0.1 to 0.5 μm, and the shape of the support surface is almost the same as that of the magnetic recording medium. The presence of coarse protrusions causes dropout.

従来、ポリエステルフィルムで問題にされてきたのは、
添加微粒子自体の大きさであり、その粒径を小さくして
表面突起を減少させることが提案されてきた。In the past, problems with polyester films were:
This refers to the size of the added fine particles themselves, and it has been proposed to reduce surface protrusions by reducing the particle size.

本発明者の検討の結果によれば、突出粒子の大きさのみ
でなく、微粒子の形状も太いに影響することが明らかに
なった。通常添加されている無機質微粒子は、部分的に
鋭角を含む多くの角を有する多面体か、あるいは微細な
突起や窪みを有する複雑な曲面からなり立っている。こ
れらの鋭角の部分、突起の部分には、均一な磁性薄膜が
形成され難く、また磁気記録媒体使用時に磁性薄膜の摩
耗を生じやすいことが顕微鏡観察により明らかになった
。逆に、これらの微粒子の頻度を大幅に低減せしめて極
力平滑化した表面に磁性薄膜を形成さぜた場合には、得
られる磁気記録媒体の走行性が悪く、斤耗も非常に大き
い結果実用に供し得ないことも明らかＫなった。According to the results of studies conducted by the present inventors, it has become clear that not only the size of the protruding particles but also the shape of the fine particles influences the thickness. The inorganic fine particles that are usually added are either polyhedrons with many corners, including some acute angles, or complex curved surfaces with minute protrusions and depressions. Microscopic observation has revealed that it is difficult to form a uniform magnetic thin film on these acute angle portions and protrusion portions, and that the magnetic thin film is likely to wear out when a magnetic recording medium is used. On the other hand, if the frequency of these fine particles is greatly reduced and a magnetic thin film is formed on a surface that is as smooth as possible, the resulting magnetic recording medium will have poor runnability and wear will be extremely large, making it impractical for practical use. It also became clear that it could not be used.

発明の目的 木兄１」ｊ者会は、−」−記の結果に基すき、多数の微
細突起を有し、しかも、その突起先端近傍に鋭角の部分
のない表面を探した結果、結晶性高分子溶液を塗布乾燥
することにより、塗膜表面が巨視的に７１スらかであシ
微視的にゆるやかな曲面を有する無数の突起から成る塗
膜を得ることができ、この塗膜を下塗り層とした基板が
磁性薄膜形成用支持体として適しており、従来の無機質
粒子を表面に突出させたフィルム基板に比べて得られる
磁気記録媒体の磁気特性、走行耐久性等が著るしく優れ
ていることを見出した。Purpose of the Invention Based on the results described in -'-, the Association of Members of the Board searched for a surface that had a large number of minute protrusions and did not have any sharp edges near the tips of the protrusions, and found that it was crystalline. By applying and drying a polymer solution, it is possible to obtain a coating film whose surface is macroscopically smooth and consists of countless protrusions with a microscopically gently curved surface. The substrate with the undercoat layer is suitable as a support for forming a magnetic thin film, and the magnetic properties and running durability of the resulting magnetic recording medium are significantly superior compared to conventional film substrates with inorganic particles protruding from the surface. I found out that

また、従来下塗シ層上に磁性層を形成せしめることは公
知であるが、その目的をしているところはいずれも、接
着強度改善あるいは単なる平滑化であって、本発明のご
とき特定形状を発現せしめてそれを磁気記録媒体の表面
形状として使用した例は見当らない。In addition, although it has been known to form a magnetic layer on an undercoat layer, the purpose of this is either to improve adhesive strength or simply smoothen the layer, but to develop a specific shape as in the present invention. At least, there is no example of using it as a surface shape of a magnetic recording medium.

ただ、エツチングによりポリエステルフィルム表面を粗
面化せしめ、その上に磁性層を形成せしめた例はあるが
、エツチング法自体、後洗浄等が必要で工程が複雑であ
るのに加え、本発明の狙いのような微視的にゆるやかな
曲面を有する突起は得られ難い。However, although there are examples of roughening the surface of a polyester film by etching and forming a magnetic layer thereon, the etching method itself requires post-cleaning, etc., and the process is complicated. It is difficult to obtain a protrusion with a microscopically gently curved surface like this.

発明の構成 すなわち本発明は、表面平滑性良好な基板上に結晶性高
分子溶液を塗布乾燥して表面粗さが高さの最高値で０．
０３〜０．５μのしわ状突起を有する下塗９層を形成せ
しめ、続いてその下塗シ層表面に強磁性薄膜を形成せし
めることにより、磁気特性、走行耐久性良好な磁気記録
媒体を製造せんとするものである。The structure of the invention, that is, the present invention is to apply a crystalline polymer solution onto a substrate with good surface smoothness and dry it, so that the surface roughness is 0.0 at the maximum height.
By forming 9 layers of undercoat having wrinkle-like protrusions of 0.03 to 0.5μ, and then forming a ferromagnetic thin film on the surface of the undercoat layer, a magnetic recording medium with good magnetic properties and running durability can be manufactured. It is something to do.

実施例の贋、１夕ｊ 本発明に使用する基板としてはポリエステルフィルン５
、ポリプロピレンフィルム、ポリアミドフィルム、ある
いは金属シート等で表面平滑性良好なもノ（りとえば、
ＪＩＳ、Ｂ−０６０１記載のＲａ値で０．０１以下のも
の）が適当で、具体例としては、写真用ポリエチレンテ
レフタレートニ軸延伸フ、ｆルムがある。False of the example, 1 evening j As the substrate used in the present invention, polyester film 5
, polypropylene film, polyamide film, or metal sheet with good surface smoothness (for example,
Those having an Ra value of 0.01 or less as described in JIS, B-0601) are suitable, and specific examples include photographic polyethylene terephthalate biaxially stretched films and f films.

基板」、に下塗り層を形成せしめるのに使用する結晶性
高分子溶液としてはポリエチレンテレフタレート、ポリ
エチレン２，６ナフタレート、ポリエチレンブチレート
、ポリエチレン−Ｐ−オキシベンゾエ−１・笠の飽１１
１ポリエステルをジクロル耐酸、オルソクロルフェノー
ル、フェノール・四塩化エタン混液等の溶媒に溶解した
ポリエステル溶液、ナイロン６、ナイロン６．６．ナイ
ロン６゜１０、ナイロン１１、ナイロン１２等をフェノ
ール、クレゾール、蟻酸等に溶解したポリアミド溶液、
ポリエチレン、ポリプロピレン、ポリメチルペンテン等
を脂肪族炭化水素に溶解したポリオレフィン溶液、ポリ
塩化ビニリデン、ポリ弗化ビニリデン等をジメチルホル
ムアミド、ジメチルアセトアミド等に溶解したポリビニ
リデン溶液等が適当であり、これらの溶液を、濃度０．
５〜２０％のの範囲で、仕上り厚さ約０．１〜０．５μ
の範囲で前記基板上に塗布し加熱乾燥することにより、
基板上に表面粗さの高さの最高値（Ｊ　Ｉ　Ｓ、　Ｂ　
−０６０１゜Ｒｍａｘ）で０．０３〜０．５μの範囲の
特定値を有する高さの揃った微細な無数のしわ状突起を
表面に有する結晶性高分子からなる下塗り層皮膜が形成
される。このしわの大きさは、結晶性高分子とその溶媒
の種類、溶液の濃度、膜厚等によシ種々変化せしめるこ
とができる。Examples of the crystalline polymer solution used to form the undercoat layer on the substrate include polyethylene terephthalate, polyethylene 2,6 naphthalate, polyethylene butyrate, and polyethylene-P-oxybenzoe-1/Kasa no Saku 11.
Polyester solution prepared by dissolving 1 polyester in a solvent such as dichloroacid resistant, orthochlorophenol, phenol/tetrachloroethane mixture, nylon 6, nylon 6.6. Polyamide solution in which nylon 6°10, nylon 11, nylon 12, etc. are dissolved in phenol, cresol, formic acid, etc.
Polyolefin solutions in which polyethylene, polypropylene, polymethylpentene, etc. are dissolved in aliphatic hydrocarbons, polyvinylidene solutions in which polyvinylidene chloride, polyvinylidene fluoride, etc. are dissolved in dimethylformamide, dimethylacetamide, etc. are suitable. , the concentration is 0.
In the range of 5-20%, the finished thickness is approximately 0.1-0.5μ
By coating it on the substrate in a range of and heating and drying it,
The maximum height of surface roughness (J I S, B
-0601°Rmax), an undercoat layer film made of a crystalline polymer having on its surface countless fine wrinkle-like protrusions of uniform height and having a specific value in the range of 0.03 to 0.5 μm is formed. The size of these wrinkles can be varied depending on the type of crystalline polymer and its solvent, the concentration of the solution, the film thickness, etc.

実施例１ ポリブチレンテレフタレートの５％ジクロル酢酸溶液を
市販の写真用ポリエチレンテレフタレートニ軸延伸フィ
ルム表面に塗布し、１５０°Ｃの熱風乾燥炉中でジクロ
ル酢酸を蒸発させしわ状突起を形成さぜた場合の下塗り
層厚さとしわ状突起の表面粗さ最大値Ｒｍａｘ　（μ）
との関係は次表のようになった。Example 1 A 5% dichloroacetic acid solution of polybutylene terephthalate was applied to the surface of a commercially available photographic polyethylene terephthalate biaxially stretched film, and the dichloroacetic acid was evaporated in a hot air drying oven at 150°C to form wrinkle-like projections. Maximum value of undercoat layer thickness and surface roughness of wrinkle-like protrusions Rmax (μ)
The relationship is as shown in the table below.

表 なお、十表の最下段は比較例に相当する。table Note that the bottom row of Table 10 corresponds to comparative examples.

一般的傾向として、下塗り層の膜厚増大につれて、まず
、しわの高さが均一に増大し、さらに膜厚を増大すると
一部分のしわの高さと幅が増大して粗大なしわに成長し
ていく。本発明で使用するしわの高さの範囲、すなわち
、ｏ、０３〜０．５μ、の場合、しわの幅は０．１〜６
μとなる。これらのしわの最大の特徴は表面が微視的に
ゆるやかな曲面を有していることと、しわ同志の高さが
比較的一定に揃っているため巨視的にしわから成る塗膜
表面が滑らかとなることである。As a general trend, as the thickness of the undercoat layer increases, the height of the wrinkles increases uniformly, and as the thickness increases further, the height and width of some wrinkles increase and grow into coarse wrinkles. . For the wrinkle height range used in the present invention, i.e. o, 03-0.5μ, the wrinkle width is 0.1-6
becomes μ. The most important feature of these wrinkles is that the surface has a microscopically gently curved surface, and the heights of the wrinkles are relatively constant, so macroscopically the coating surface made up of wrinkles is smooth. It is what happens.

しわ状突起を有する下塗り層の表面に強磁性薄膜を形成
せしめる方法としては、通常の電気メッキ、無電解メッ
キ、真空蒸着、スパツタリング。Methods for forming a ferromagnetic thin film on the surface of the undercoat layer having wrinkle-like protrusions include conventional electroplating, electroless plating, vacuum deposition, and sputtering.

イオンブレーティング等が適用できる。Ion brating etc. can be applied.

なお、下塗９層表面の表面粗さ最高値が０．０３μ未満
であると、得られる磁気記録媒体の表面の滑りが悪く、
また、０．５μを超える値では磁気ノイズが増大するた
め具合が悪い。Note that if the maximum surface roughness of the surface of the 9 undercoat layers is less than 0.03μ, the surface of the obtained magnetic recording medium will have poor slippage.
On the other hand, a value exceeding 0.5μ increases magnetic noise, which is undesirable.

実施例２ 市販の厚さ２６μの写真用ポリエチレンテレフタレート
ニ軸延伸フィルムの両面に、そのフィルムをジクロル酢
酸に重量比で３％溶解させた溶液を塗布し１６Ｑ″Ｃで
乾燥して仕上り厚さ０．３μの塗膜を形成させた。この
ものの表面粗さは、最大高さで０．２μであり、約３μ
の幅を有するしわが無数形成されていた。このものの片
面に真空蒸着によりコバルト強磁性薄膜（厚さ約０．２
μ）を形成させ、続いて所定幅に切断して磁気テープと
した。このものを市販のカートリッジ型ビデオテープレ
コーダーを用いて繰り返し再生試験を行なったところ、
２０回の繰゛り返し後において画質は良好であり、ドロ
ップアウト数も１０分間に１個以内であった。Example 2 A solution prepared by dissolving 3% by weight of the film in dichloroacetic acid was applied to both sides of a commercially available biaxially stretched photographic polyethylene terephthalate film with a thickness of 26μ, and dried at 16Q''C to a finished thickness of 0. A coating film with a thickness of .3μ was formed.The surface roughness of this material was 0.2μ at the maximum height, and approximately 3μ.
Numerous wrinkles with a width of . A cobalt ferromagnetic thin film (approximately 0.2
μ) was formed and then cut into a predetermined width to obtain a magnetic tape. When this product was repeatedly played back using a commercially available cartridge type video tape recorder,
After 20 repetitions, the image quality was good and the number of dropouts was within 1 per 10 minutes.

実施例３ 市販の厚さ３０μの二軸延伸ポリプロピレンの片面に、
そのフィルムを灯油に重量、比で１％溶解させた溶液を
塗布し１２０’Ｃで乾燥して厚さ約０．５μのしわ状皮
膜を形成させた。その表面粗さは最大高さ０．４μで、
約２μの幅を有するしわが無数形成されていた。この表
面に実施例１と同様に磁ゼ１′Δ、り膜を形成さぜ、実
施例１と同様の試験を行ない、同様の結果を得た。Example 3 On one side of commercially available biaxially oriented polypropylene with a thickness of 30μ,
The film was coated with a solution prepared by dissolving 1% by weight in kerosene and dried at 120'C to form a wrinkled film with a thickness of about 0.5 microns. Its surface roughness has a maximum height of 0.4μ,
Numerous wrinkles with a width of about 2 μm were formed. A magnetic zeolite 1'Δ film was formed on this surface in the same manner as in Example 1, and the same tests as in Example 1 were conducted to obtain similar results.

実施例４ 実施例１で使用したポリエステルフィルムの片面に、ナ
イロン６０２％フェノール溶液を塗布して１６０°Ｃに
て乾燥し、最大高さ０．０６μ、しわの幅約１μの緻密
なしわ状表面を有する表面を得た。この表面にコバルト
強磁性薄膜を蒸着したのち、このフィルムの裏面に滑り
住改善のためナイロン１２の１０％フェノール溶液を塗
布した最大高さ０．７μのしわ状表面を形成させたのち
磁気テープとし、実施例１と同様の試験を行なったとこ
ろ、５０回の繰シ返し後において画質は良好でドロップ
アウトはみられなかった。Example 4 A nylon 602% phenol solution was applied to one side of the polyester film used in Example 1 and dried at 160°C to form a dense wrinkled surface with a maximum height of 0.06μ and a wrinkle width of approximately 1μ. A surface with . After depositing a cobalt ferromagnetic thin film on this surface, a wrinkled surface with a maximum height of 0.7 μm was formed on the back side of this film by applying a 10% phenol solution of nylon 12 to improve the slip resistance. When the same test as in Example 1 was conducted, the image quality was good and no dropout was observed after 50 repetitions.

比較例１ 実施例３において、磁性面側のしわの最大高さが０．０
１μとなるようにナイロン膜を調整した場合には、磁気
テープの滑り性が悪く、画像の乱れを生じた。Comparative Example 1 In Example 3, the maximum height of wrinkles on the magnetic surface side was 0.0
When the nylon film was adjusted to have a thickness of 1 μm, the slipperiness of the magnetic tape was poor and the image was distorted.

比較例２ 実施例１において、しわ形成溶液としてポリブチレンチ
レフゲートの６％ジクロル酢酸溶液を用い、しわの最大
高さ０７μの表面を形成させた場合には、磁気テープの
ノイズレベル上昇による画質の低下がみられた。Comparative Example 2 In Example 1, when a 6% dichloroacetic acid solution of polybutylene lentil gate was used as the wrinkle forming solution to form a surface with a maximum wrinkle height of 07 μm, the image quality decreased due to an increase in the noise level of the magnetic tape. A decrease was observed.

発明の効果 以上より明らかなように、本発明の製法によれば、磁気
特性、走行耐久性に優れた磁気記録媒体を容易に再現良
く製造することができるため本発明の工業的価値は非常
に大きいものである。Effects of the Invention As is clear from the above, according to the manufacturing method of the present invention, a magnetic recording medium with excellent magnetic properties and running durability can be easily manufactured with good reproducibility, so the industrial value of the present invention is extremely high. It's big.

Claims (1)

【特許請求の範囲】[Claims] 表面平滑性良好な基板上に結晶性高分子溶液を塗布乾燥
して表面粗さが高さの最高値で０．０３〜０．５μのし
わ状突起を有する下塗り層を形成せしめ、続いてその下
塗り層表面に強磁性薄膜を形成せしめることを特徴とす
る磁気記録媒体の製造方法。A crystalline polymer solution is coated on a substrate with good surface smoothness and dried to form an undercoat layer having wrinkle-like protrusions with a surface roughness of 0.03 to 0.5μ at the highest value. A method for manufacturing a magnetic recording medium, comprising forming a ferromagnetic thin film on the surface of an undercoat layer.